Improving the spectral purity of single photons by a single-interferometer-coupled microring

We experimentally engineer a high-spectral-purity single-photon source using a single-interferometer-coupled silicon microring. By the reconfiguration of the interferometer, different coupling conditions can be obtained, corresponding to different quality factors for the pump and signal/idler. The ratio between the quality factor of the pump and signal/idler ranges from 0.29 to 2.57. By constructing the signal–idler joint spectral intensity, we intuitively demonstrate the spectral correlation of the signal and idler. As the ratio between the quality factor of the pump and signal/idler increases, the spectral correlation of the signal and idler decreases, i.e., the spectral purity of the signal/idler photons increases. Furthermore,time-integrated second-order correlation of the signal photons is measured, giving a value up to 94.95 ± 3.46%. Such high-spectral-purity photons will improve the visibility of quantum interference and facilitate the development of on-chip quantum information processing.

Exploiting Loop-Carried Stream Reuse for Scientific Computing Applications on the Stream Processor

Compared with other stream applications, scientific stream programs are usually bound by memory accesses. Reusing streams across different iterations, i.e. loop-carried stream reuse, can effectively improve the SRF locality, thus reducing memory accesses greatly. In the paper, we first present the algorism identifying loop-carried stream reuse and that exploiting the reuse after analyzing scientific computing applications. We then perform several representative microbenchmarks and scientific stream programs with and without our optimization on Isim, a cycle-accurate stream processor simulator. Experimental results show that our algorithms can effectively exploit loop-carried stream reuse for scientific stream programs and thus greatly improve the performance of memory-bound scientific stream programs.

Diffuse midline glioma treated with epigenetic agent-based immunotherapy

Dear Editor,Diffuse midline glioma,H3K27-altered(DMG),is a pediatric-type high-grade diffuse glioma that preferentially localizes to the brainstem or pons,thalamus,and spinal cord.Surgical resection is challenging and biopsy is often performed in most cases.To date,no conventional,targeted or immune therapy has been convincingly shown to improve patients’overall survival(OS).

Bright photon-pair source based on a silicon dual-Mach-Zehnder microring

Single photons and photon pairs are typically generated by spontaneous parametric down conversion or quantum dots;however,spontaneous four-wave mixing(SFWM)in silicon microring resonators[1]is also an appealing source of entangled photons,offering a strong cavity-enhanced nonlinear interactions while maintaining features,such as compact,simple to fabricate,and allowing for thermal tuning.However,silicon ring-resonators usually suffer from a trade-off between providing a high pair generation rate(PGR)and high extraction efficiency.To achieve high PGR,devices are generally operated with the signal and idler photons in the undercoupling regime and pump photons at the critical coupling point,while high extraction rates require the converted photons to be overcoupled.Therefore,the optimal conditions for achieving maximal output photon pair flux are critical coupling for the pump photons and overcoupling for the converted photons[2,3].

A Bayesian validation approach to practical boson sampling

Boson sampling is a promising candidate for demonstrating quantum supremacy. The validation that involves judging whether a quantum setup outputs photons following the boson sampling model is an essential task in the experiments. However, the current validation methods may result in an incorrect conclusion being reached in realistic experiments, in which no ideally identical photons exist. Accordingly, this study proposes a slope-based approach, which is an extended Bayesian validation, to model the degree of photon indistinguishability. Through numerical simulations and performance evaluations, we demonstrate that the proposed approach can correctly validate boson sampling against the distribution of classical particles. In addition to offering a useful approach for validation, our research indicates that physicists should pay more attention to the quality of photon indistinguishability in boson sampling experiments.

Ecological role of physical dormancy in seeds of Oxytropis racemosa in a semiarid sandland with unpredictable rainfall

Aims Seed dormancy and the soil seed bank are crucial to plant regeneration strategy,especially in semiarid ecosystems with unpredictable precipi-tation.the aim of this study was to investigate how seed dormancy is controlled by environmental factors and how it is correlated with the soil seed bank and regeneration of the perennial legume Oxytropis race-mosa,a dominant perennial herb in Mu Us Sandland of semiarid China.Methods Germination and imbibition experiments on fresh intact and scarified seeds of O.racemosa were used to identify physical dormancy(PY)in seeds of this species.Soil seed bank dynamics,timing of seedling emer-gence and the fate of buried seeds in the natural habitat were investigated.Important Findings PY was broken by mechanical scarification or wet heat/ice water cycles but not solely by dry heat or wet heat treatment.the soil seed bank exhibited seasonal changes in the number of seeds,which was highest in September and lowest in July.Seeds buried at different sand depths gradually lost dormancy;20-42%of the seeds remained dormant after 20 months of burial.Dormancy break occurs grad-ually throughout the year.Our results indicate that O.racemosa exhibits hardcoatedness heterogeneity that spreads germination of a seed cohort between seasons and years in the semiarid environ-ment,where the amount of precipitation during the growing season is highly variable.

Relationship Between Perisylvian Essential Language Sites and Arcuate Fasciculus in the Left Hemisphere of Healthy Adults

Essential language sites and the arcuate fasciculus（AF） have been extensively researched. However, the relationship between them remains insufficiently studied,especially in healthy people. Navigated transcranial magnetic stimulation（n TMS） is increasingly used in language mapping. While enjoying the advantage of non-invasiveness, it is also capable of inducing a virtual lesion in the brain. Thus, it offers the possibility of using the virtuallesion method to study the healthy brain. This study combined n TMS and diffusion tensor imaging（DTI）tractography to investigate the relationship between essential language sites and the AF in 30 healthy right-handedvolunteers. A total of 143 essential language sites were identified using n TMS, and a total of 175 AF terminations were identified using DTI tractography. Sixty-six sites had a direct correlation with the AF, accounting for 46% of the total essential language sites. Forty-seven AF terminations harbored essential language sites, accounting for 27% of the total AF terminations. Upon data rendering to the cortical parcellation system, a region-related heterogeneity of the correlation rate was found. This study provides the first data on the relationship between essential language sites and the AF in healthy adults.

A study on sublabial transsphenoidal treatment of pituitary tumor under microscope with aid of endoscope

Background: A pituitary tumor is a tumor with a high incidence among brain tumors. Microscopic traditional STT approach with aid of endoscope has a high therapeutic effect and few complications. Methods: The authors reviewed 146 patients who underwent STT resection of sellar masses between January 1, 2006, and December 31, 2013. From this group, 40 patients who underwent microscopic STT surgery with aid of endoscope were included in the study. In this series, there were many nonfunctional and Growth Hormone(GH) secreting adenoma. In the study group, tumor size ranged from 60 to 79 mm in 3 cases. Pathophysiological studies, tumor sizes, clinical outcomes, extent of resection, visual function and complication were estimated. Results: In our study, gross-total resection(GTR) was achieved in 33 patients (82.5%), subtotal in 3 (7.5%), and partial in 4 (10%). Visual acuity were improved in 82.1%, while 17.9% were unchanged. Visual fields were improved in 81.2%. No deaths occurred in this cohort of patients. Conclusions: Pituitary adenoma surgery under microscope with aid of endoscope is an effective treatment method, which results in high (>90%) rates of resection. It is not associated with high rates of major complications and is safe when performed by experienced surgeons.

Optimal subsystem approach to multi-qubit quantum state discrimination and experimental investigation

quantum computing;;quantum measurement;;quantum state discrimination;;entanglement;;reduced density

Experimental demonstration of quantum transport enhancement using time-reversal symmetry breaking on a silicon photonic chip

The continuous-time quantum walk is a basic model for studying quantum transport and developing quantum-enhanced algorithms. Recent studies show that by introducing a phase into the standard continuous-time quantum walk model, the time-reversal symmetry can be broken without changing the Hermitian property of the Hamiltonian. The time-reversal symmetry breaking quantum walk shows advantages in quantum transport, such as perfect state transfer, directional control, transport speedup, and quantum transport efficiency enhancement. In this work, we implement the time-reversal symmetry breaking quantum walks on a reconfigurable silicon photonic chip and demonstrate the enhancement introduced by breaking time-reversal symmetry. Perfect state transfer on a three-site ring, a quantum switch implemented on a six-site graph, and transport speedup using a linear chain of triangles are demonstrated with high fidelity. Time-reversal asymmetry has also been used in a simplified light-harvesting model,implying the potential of time-reversal symmetry breaking in photosynthesis investigations.

CACA guidelines for holistic integrative management of glioma

Glioma of the brain is a kind of tumor originating from neuroglial cells.It is the most common primary intracranial tumor,accounting for~30%of all central nervous system tumors and 80% of malignant brain tumors.Glioma is characterized by high disability and recurrence rates.The disease seriously threatens the life of patients,afects their quality of life,and brings a heavy economic and psychological burden to patients,families,and society.With the progression of molecular genetic testing technology and the completion of various clinical trials,the classifcation scheme for glioma is increasingly well established.Diagnosis and treatment regimens,including traditional and new regimens,are becoming increasingly specialized and standardized.The purpose is to develop a clinical diagnosis and treatment guideline for glioma in the Chinese population suitable for Chinese doctors and the general population based on domestic and international glioma research progress.Thus,domestic practitioners in the feld can obtain current information and provide better service to patients with glioma,promoting the development of domestic clinical medicine and basic research on glioma.